sys/vm/device_pager.c

   1 /*
   2  * Copyright (c) 1990 University of Utah.
   3  * Copyright (c) 1991, 1993
   4  *      The Regents of the University of California.  All rights reserved.
   5  *
   6  * This code is derived from software contributed to Berkeley by
   7  * the Systems Programming Group of the University of Utah Computer
   8  * Science Department.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. All advertising materials mentioning features or use of this software
  19  *    must display the following acknowledgement:
  20  *      This product includes software developed by the University of
  21  *      California, Berkeley and its contributors.
  22  * 4. Neither the name of the University nor the names of its contributors
  23  *    may be used to endorse or promote products derived from this software
  24  *    without specific prior written permission.
  25  *
  26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  36  * SUCH DAMAGE.
  37  *
  38  *      @(#)device_pager.c      8.1 (Berkeley) 6/11/93
  39  * $FreeBSD: src/sys/vm/device_pager.c,v 1.46.2.1 2000/08/02 21:54:37 peter Exp $
  40  * $DragonFly: src/sys/vm/device_pager.c,v 1.13 2008/01/21 10:25:18 corecode Exp $
  41  */
  42
  43 #include <sys/param.h>
  44 #include <sys/systm.h>
  45 #include <sys/kernel.h>
  46 #include <sys/conf.h>
  47 #include <sys/mman.h>
  48 #include <sys/device.h>
  49 #include <sys/queue.h>
  50 #include <sys/malloc.h>
  51 #include <sys/thread2.h>
  52
  53 #include <vm/vm.h>
  54 #include <vm/vm_object.h>
  55 #include <vm/vm_page.h>
  56 #include <vm/vm_pager.h>
  57 #include <vm/vm_zone.h>
  58
  59 static vm_object_t dev_pager_alloc (void *, off_t, vm_prot_t, off_t);
  60 static void dev_pager_dealloc (vm_object_t);
  61 static int dev_pager_getpage (vm_object_t, vm_page_t *, int);
  62 static void dev_pager_putpages (vm_object_t, vm_page_t *, int,
  63                 boolean_t, int *);
  64 static boolean_t dev_pager_haspage (vm_object_t, vm_pindex_t);
  65
  66 /* list of device pager objects */
  67 static TAILQ_HEAD(, vm_page) dev_freepages_list =
  68                 TAILQ_HEAD_INITIALIZER(dev_freepages_list);
  69 static MALLOC_DEFINE(M_FICTITIOUS_PAGES, "device-mapped pages", "Device mapped pages");
  70
  71 static vm_page_t dev_pager_getfake (vm_paddr_t);
  72 static void dev_pager_putfake (vm_page_t);
  73
  74 static int dev_pager_alloc_lock, dev_pager_alloc_lock_want;
  75
  76 struct pagerops devicepagerops = {
  77         dev_pager_alloc,
  78         dev_pager_dealloc,
  79         dev_pager_getpage,
  80         dev_pager_putpages,
  81         dev_pager_haspage
  82 };
  83
  84 static vm_object_t
  85 dev_pager_alloc(void *handle, off_t size, vm_prot_t prot, off_t foff)
  86 {
  87         cdev_t dev;
  88         vm_object_t object;
  89         unsigned int npages;
  90         vm_offset_t off;
  91
  92         /*
  93          * Make sure this device can be mapped.
  94          */
  95         dev = handle;
  96
  97         /*
  98          * Offset should be page aligned.
  99          */
 100         if (foff & PAGE_MASK)
 101                 return (NULL);
 102
 103         size = round_page(size);
 104
 105         /*
 106          * Check that the specified range of the device allows the desired
 107          * protection.
 108          *
 109          * XXX assumes VM_PROT_* == PROT_*
 110          */
 111         npages = OFF_TO_IDX(size);
 112         for (off = foff; npages--; off += PAGE_SIZE) {
 113                 if (dev_dmmap(dev, off, (int)prot) == -1)
 114                         return (NULL);
 115         }
 116
 117         /*
 118          * Lock to prevent object creation race condition.
 119          */
 120         while (dev_pager_alloc_lock) {
 121                 dev_pager_alloc_lock_want++;
 122                 tsleep(&dev_pager_alloc_lock, 0, "dvpall", 0);
 123                 dev_pager_alloc_lock_want--;
 124         }
 125         dev_pager_alloc_lock = 1;
 126
 127         /*
 128          * Look up pager, creating as necessary.
 129          */
 130         object = dev->si_object;
 131         if (object == NULL) {
 132                 /*
 133                  * Allocate object and associate it with the pager.
 134                  */
 135                 object = vm_object_allocate(OBJT_DEVICE,
 136                         OFF_TO_IDX(foff + size));
 137                 object->handle = handle;
 138                 TAILQ_INIT(&object->un_pager.devp.devp_pglist);
 139                 dev->si_object = object;
 140         } else {
 141                 /*
 142                  * Gain a reference to the object.
 143                  */
 144                 vm_object_reference(object);
 145                 if (OFF_TO_IDX(foff + size) > object->size)
 146                         object->size = OFF_TO_IDX(foff + size);
 147         }
 148
 149         dev_pager_alloc_lock = 0;
 150         if (dev_pager_alloc_lock_want)
 151                 wakeup(&dev_pager_alloc_lock);
 152
 153         return (object);
 154 }
 155
 156 static void
 157 dev_pager_dealloc(vm_object_t object)
 158 {
 159         vm_page_t m;
 160         cdev_t dev;
 161
 162         if ((dev = object->handle) != NULL) {
 163                 KKASSERT(dev->si_object);
 164                 dev->si_object = NULL;
 165         }
 166         KKASSERT(object->swblock_count == 0);
 167
 168         /*
 169          * Free up our fake pages.
 170          */
 171         while ((m = TAILQ_FIRST(&object->un_pager.devp.devp_pglist)) != 0) {
 172                 TAILQ_REMOVE(&object->un_pager.devp.devp_pglist, m, pageq);
 173                 dev_pager_putfake(m);
 174         }
 175 }
 176
 177 static int
 178 dev_pager_getpage(vm_object_t object, vm_page_t *mpp, int seqaccess)
 179 {
 180         vm_offset_t offset;
 181         vm_paddr_t paddr;
 182         vm_page_t page;
 183         cdev_t dev;
 184         int prot;
 185
 186         page = *mpp;
 187         dev = object->handle;
 188         offset = page->pindex;
 189         prot = PROT_READ;       /* XXX should pass in? */
 190
 191         paddr = pmap_phys_address(
 192                     dev_dmmap(dev, (vm_offset_t)offset << PAGE_SHIFT, prot));
 193         KASSERT(paddr != -1,("dev_pager_getpage: map function returns error"));
 194
 195         if (page->flags & PG_FICTITIOUS) {
 196                 /*
 197                  * If the passed in reqpage page is a fake page, update it
 198                  * with the new physical address.
 199                  */
 200                 page->phys_addr = paddr;
 201                 page->valid = VM_PAGE_BITS_ALL;
 202         } else {
 203                 /*
 204                  * Replace the passed in reqpage page with our own fake page
 205                  * and free up all the original pages.
 206                  */
 207                 page = dev_pager_getfake(paddr);
 208                 TAILQ_INSERT_TAIL(&object->un_pager.devp.devp_pglist, page, pageq);
 209                 crit_enter();
 210                 vm_page_free(*mpp);
 211                 vm_page_insert(page, object, offset);
 212                 crit_exit();
 213         }
 214         return (VM_PAGER_OK);
 215 }
 216
 217 static void
 218 dev_pager_putpages(vm_object_t object, vm_page_t *m,
 219                    int count, boolean_t sync, int *rtvals)
 220 {
 221         panic("dev_pager_putpage called");
 222 }
 223
 224 static boolean_t
 225 dev_pager_haspage(vm_object_t object, vm_pindex_t pindex)
 226 {
 227         return (TRUE);
 228 }
 229
 230 static vm_page_t
 231 dev_pager_getfake(vm_paddr_t paddr)
 232 {
 233         vm_page_t m;
 234
 235         if ((m = TAILQ_FIRST(&dev_freepages_list)) != NULL) {
 236                 TAILQ_REMOVE(&dev_freepages_list, m, pageq);
 237         } else {
 238                 m = kmalloc(sizeof(*m), M_FICTITIOUS_PAGES, M_WAITOK);
 239         }
 240         bzero(m, sizeof(*m));
 241
 242         m->flags = PG_BUSY | PG_FICTITIOUS;
 243         m->valid = VM_PAGE_BITS_ALL;
 244         m->dirty = 0;
 245         m->busy = 0;
 246         m->queue = PQ_NONE;
 247         m->object = NULL;
 248
 249         m->wire_count = 1;
 250         m->hold_count = 0;
 251         m->phys_addr = paddr;
 252
 253         return (m);
 254 }
 255
 256 /*
 257  * Synthesized VM pages must be structurally stable for lockless lookups to
 258  * work properly.
 259  */
 260 static void
 261 dev_pager_putfake(vm_page_t m)
 262 {
 263         if (!(m->flags & PG_FICTITIOUS))
 264                 panic("dev_pager_putfake: bad page");
 265         KKASSERT(m->object == NULL);
 266         TAILQ_INSERT_HEAD(&dev_freepages_list, m, pageq);
 267 }
 268